Quantitative Feedback Referencing for Improved Kinetic Fitting of Scanning Electrochemical Microscopy Measurements

Scanning electrochemical microscopy (SECM) has matured as a technique for studying local electrochemical processes. The feedback mode is most commonly used for extracting quantitative kinetic information. However, approaching individual regions of interest, as is commonly done, does not take full ad...

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Bibliographic Details
Published in:Analytical chemistry (Washington) 2022-10, Vol.94 (40), p.13852-13859
Main Authors: Skaanvik, Sebastian Amland, Stephens, Lisa Irene, Gateman, Samantha Michelle, Geissler, Matthias, Mauzeroll, Janine
Format: Article
Language:English
Subjects:
Chemistry
Curve fitting
Electrochemistry
Electrochemistry - methods
Feedback
Kinetics
Microelectrodes
Microscopy
Microscopy, Electrochemical, Scanning
Negative feedback
Positive feedback
Referencing
Scanning
Silicon Dioxide
Spatial discrimination
Spatial resolution
Substrates
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Summary:Scanning electrochemical microscopy (SECM) has matured as a technique for studying local electrochemical processes. The feedback mode is most commonly used for extracting quantitative kinetic information. However, approaching individual regions of interest, as is commonly done, does not take full advantage of the spatial resolution that SECM has to offer. Moreover, fitting of experimental approach curves remains highly subjective due to the manner of estimating the tip-to-substrate distance. We address these issues using negative or positive feedback currents as a reference to calculate the tip-to-substrate distance directly for quantitative kinetic fitting of approach curves and line profiles. The method was first evaluated by fitting simulated data and then tested experimentally by resolving negative feedback and intermediate kinetics behavior in a spatially controlled fashion using (i) a flat, binary substrate composed of Au and SiO2 segments and (ii) a dual-mediator system for live-cell measurements. The methodology developed herein, named quantitative feedback referencing (QFR), improves fitting accuracy, removes fitting subjectivity, and avoids substrate–microelectrode contact.
ISSN:0003-2700
1520-6882
DOI:10.1021/acs.analchem.2c02498